Five moon bears have been freed from a bile farm in Vietnam after more than 21 years in captivity, in one of the most harrowing cases of animal cruelty seen by the animal welfare group that lead the rescue.

Hong Kong-based Animals Asia carried out the rescue last week, freeing the bears from barren concrete cells with rusted bars where they had been kept for more than two decades. A vet said the bears had decayed teeth from decades of poor diet, and from biting their cage bars in frustration.

After a five-day journey, the bears – LeBon, Kim, Mai, Star, and Mekong – are now at the organisation’s Vietnam Bear Rescue Centre, a sanctuary in Tam Dao National Park. Moon bears are listed as vulnerable by the International Union for Conservation of Nature, and categorised as endangered by CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), which is an international agreement between governments.

Its aim is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.

Animals Asia’s Vietnam director Tuan Bendixsen, who oversaw the rescue, said: “Ending bear bile farming in Vietnam will require the cooperation of NGOs and government departments and that’s exactly how these five individuals have been freed from so many years of cruelty.”

Jill Robinson, Animals Asia founder, says the bears need urgent care to overcome physical and psychological trauma. “Their healing starts now and Vietnam is a step closer to the end of a cruel industry which has blighted the country’s reputation for too long.”

In 2017, Animals Asia signed a groundbreaking deal with the Vietnamese government to relocate the around 800 bears who remain on farms in the country to sanctuaries.

So far Animals Asia has rescued 177 bears from farms in Vietnam. There were about 1,200 bears in captivity in Vietnam in 2017, down from more than 4,000 in 2005, caged in more than 400 bear farms across the country.

In Asia, more than 10,000 bears (mostly moon bears, but also sun bears and brown bears) are held in poor conditions on bear bile farms. Bear bile is extracted – often continuously and painfully – from their gallbladders and used in traditional medicine.

The bile is turned into powders, ointments and capsules which traditional Chinese medicine practitioners claim can ease the pain from liver disease.